At least some known gas turbine engines include a combustor, a compressor, and/or turbines that include a rotor disk that includes a plurality of rotor blades, or buckets, that extend radially outward therefrom. The plurality of rotating turbine blades or buckets channel high-temperature fluids, such as combustion gases or steam, through either a gas turbine engine or a steam turbine engine. The roots of at least some known buckets are coupled to the disk with dovetails that are inserted within corresponding dovetail slots formed in the rotor disk to form a bladed disk, or “blisk.” Because such turbine engines operate at relatively high temperatures and may be relatively large, the operating capacity of such an engine may be at least partially limited by the materials used in fabricating the buckets and/or the length of the airfoil portions of the buckets. To facilitate enhanced performance, at least some engine manufacturers have increased the size of the engines, thus resulting in an increase in the length of the airfoil portion of the buckets. Such an increase can require the size of the dovetails and the dovetail slots to be increased to ensure the longer buckets are retained in position.
With or without repairable and/or replaceable airfoil tip portions, turbine bucket assemblies are subjected to a variety of forces. Such forces require different portions of the turbine bucket assemblies to have different properties. It is known that variation of density can provide benefit, depending upon the position of the material. However, further characterization of properties providing beneficial results, especially relating to specific materials, would provide additional benefits.
A turbine bucket assembly and turbine system having a turbine bucket assembly with improvements would be desirable in the art.